1. Field of the Invention
This invention relates to a presentation server which enables a client device to run a network based application client software enabling a client to run a network based application. It finds particular utility in enterprise computing. A ‘presentation server’ is generally any kind of server that determines how data will be displayed on a client device.
2. Description of the Prior Art
Enterprise computing was originally conducted through large mainframe computers. These mainframes gave the end-user very limited application functionality, displaying only text messages and requiring keyboard strokes for every command (for example, there was no mouse and none of the richness of today's desktop applications like drag and drop, graphing, sorting or personalized settings). Deployment costs were also very high due to the cost of hardware and the lack of skilled computer operators.
The evolution to client/server-based computing provided much richer functionality. The graphical user interface (GUI) provided end-users a much simpler, more efficient method to interact with applications, but systems still proved expensive and difficult to maintain. In theory, applications would be deployed on the server centrally and distributed via the network to each of the clients. But business users had different needs of functionality and therefore required different applications with unique configurations. Not only did some information have to be personalized, but information also had to be retained on the desktop. This meant it was not possible to “write once and deploy many”. The result was that the end-user got the desired rich functionality, but much of the code for the business logic for the applications was located on individual clients. IT Departments' budgets ballooned due to high support costs and slow implementation times. Rolling out new applications—or even minor updates—required a unique installation for every PC that required access.
The advent of the Internet was supposed to change all this. The Internet provided an infrastructure that lent itself to the notion of zero-cost deployment with the promise of “write once, run anywhere”. Such a model would significantly decrease the cost of deploying enterprise systems. With the Internet, back-end servers would run the application centrally, and all that users required to access the application was a browser. There would be no code specific to the application running on the user's client. The potential this promised to large companies was unprecedented.
Despite the enormous potential, the initial technology (HTML) used for building and deploying the front-end of these new Internet applications was never intended for anything more than displaying simple text. As companies tried to deploy sophisticated business systems over the Internet, they soon realized that much of the desired functionality they wanted was not feasible. HTML based Web Applications did not have true interactivity or access to data in real-time. Business users needed to interact with and manipulate the data, but mostly what they saw was static page views. Certain solutions were designed to provide a more interactive user interface. However, they still used variations of HTML, resulting in passive documents with numerous limitations.
Specifically, from a technical perspective these limitations resulted in:                Lack of functionality: No matter how sophisticated the back-end business logic, end-users lost the functionality they had come to expect from their familiar client/server-based system. Large online systems that were deployed severely lacked the rich functionality that companies demanded in their offline systems. While lots of money was spent on building these systems, to date they have dearly not replaced client/server systems. In fact, very few even augment the existing offline systems, and in retrospect proved to be very expensive IT exercises which fell short of their original promise. There have been early attempts at providing a richer user interface and a more robust connection between the back-end servers and the client by using JavaScript, DHTML, and various plug-ins. However, these solutions present expensive development cycles and ongoing maintenance, while introducing new security issues (see below), and applications that still fall short of the desired functionality.        Load on back-end Servers: The HTML-based Web represents a very inefficient use of computing resources. Publishing HTML's required page by page structure means that as more people log on to a system, requests to the database and the application server put a strain on these servers. Companies needing to scale operations can buy more servers with more CPUs to handle the high load, but each additional processor not only costs a lot, but may also affect the license cost of all the various software packages running on the server.        Security Concerns: Companies are concerned that data pushed beyond corporate firewalls onto the Internet is open to unauthorized, third-party scrutiny. Additionally, there is concern that plug-ins downloaded from various Internet applications may contain viruses. Most software companies license their software on a per-CPU basis. As companies add more CPUs to their servers or add entirely new servers, the licensing fee for each piece of software increases by a multiple of how many new processors are added.        Cannot Easily Prototype New Features: Given the complexity of developing user interfaces that provide adequate functionality and the effort required to integrate such solutions to the back-end, companies typically do not prototype and roll out new features incrementally. Very often, further development of these systems is an extensive project, which introduces the uncertainty of never being fully deployed and used. Because of the effort required for each release, many companies shy away entirely from going forward on certain projects as opposed to rapidly developing incremental pieces to see what parts work.        
From a business manager's perspective, these limitations meant:                Inadequate Systems for Doing Business: Client/server-based systems were expensive, difficult to build and deploy and not accessible outside of the enterprise. However, they do provide the functionality needed to actually do business, whether for trading financial instruments, managing resources and accounts through ERP systems or selling and maintaining client relationships through SFA and CRM tools. A fraction of these capabilities are available over the Internet in certain systems, but are far from giving the functionality people require to be effective.        Slow Performance: Sites using HTML force users to click and wait for a response while the back-end system processes the information and pushes a new page to the users. This can take a few seconds at best, or tens of seconds, even minutes, at worst. Users of these systems simply abandon activities when they take too long or when connections entirely fail.        Expensive Development: Building and deploying enterprise-level systems over the Internet with sophisticated functionality requires a lot of custom coding with long and expensive development cycles. Most of this work cannot be leveraged for other systems and is a large, one-off expense that companies must absorb.        Expensive Maintenance: Complex Web systems contain thousands of lines of code on both the back-end (business logic) and the front-end (delivers the interface). The connection between the front-end and backend also contains thousands of lines of custom code which needs to be debugged and maintained. All changes to the code require programmers to manually write new code and test the functionality through staging before going to a live production site.        Expensive Bandwidth: In today's online systems, information is presented to users through entire Web pages, which are pushed out to users over the network. As information changes or transactions are completed, users can request new pages or submit pages back to the system. However, every time pages are sent across the network, companies pay for the bandwidth used. As online systems add users and these users start to do more activities online, they consume more and more bandwidth, and as a result costs increase quickly.        Mobile Access: As the reach of the Internet extends beyond the PC, enabling mobile access (i.e. PDAs, Cellular Phones) to business applications is becoming a standard business requirement. Current solutions for wireless delivery require separate application re-writes (and expertise) for each device supported.        Hiring and Retraining expensive IT Staff: Integration of Web systems with existing offline systems and the maintenance of more sophisticated user interfaces for the Web using JavaScript and HTML typically requires armies of programmers, burdening the budget of every department, and many times putting the overall company's viability in jeopardy.        
As a result of these challenges experienced to date, companies still have limited confidence in deploying their systems through the Web. Re-creating the same feature-rich interfaces that existed on client/server-based desktop applications has proven futile for companies attempting to move their systems to the Internet Replicating the performance of desktop applications as well as standardizing the collaboration and interaction between disparate Web applications has been even more complex, expensive, and mostly elusive. The massive trade-off in end-user productivity, combined with security, scalability and performance concerns, has resulted in enterprises running client/server systems in parallel with Web-enabled systems, further deepening the cost of IT, and still not realizing most of the benefits the Internet promised.
Hence, even though millions of people are now using the Internet to look at documents from anywhere in the world, true interactivity to manipulate data is missing, and the evolution of the Web into a mainstream business and trading environment simply has not happened.